JPS61246897A - Alarm with mounting prevention means at projecting/light receiving section - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field] The present invention relates to an alarm for a fire or theft prevention device, which is equipped with means for preventing contamination in the light emitting and receiving portions.

[Prior art]

Conventionally, in a radiation type fire detector installed in a road tunnel, for example, as shown in FIG. 22' was installed. Floating dust collides with this dustproof plate 22' and falls to prevent the light receiving window 21' from getting dirty, thereby reducing the number of times of cleaning.

[Problems with conventional technology]

However, in the case where the plate-shaped dustproof plate 22' is provided, when the airflow 3 overcomes the dustproof plate 22', the downstream side becomes negative pressure and the airflow descends as shown by the arrow 31', so that the main flow of the airflow is The flow is as shown by arrow 32', and dust can only be prevented from adhering to the light receiving window 21' up to a position slightly higher than the height of the dustproof plate 22'. Therefore, in a detector with a wide field of view, the provision of a dustproof plate may restrict the field of view and reduce the functionality of the detector.

[Means for solving problems]

In view of the above points, this invention has a 7-shape, an H-shape, or a U-shape that generates an upward airflow on the upstream side of the air flow of the light emitting/light receiving part so that the airflow does not directly collide with the light emitting/light receiving part. The invention is characterized in that a change plate is provided.

[For production]

The alarm of the present invention has the above-mentioned characteristic configuration, so that the airflow flowing inside the 7-, H-, or U-shaped change plate collides at the tip and overcomes it, generating negative pressure on the downstream side. Since the airflow flowing outside the change plate wraps around and lifts it up, an upward air current is generated, so that the light emitting/receiving section is protected up to approximately twice the height of the change plate.

[Embodiment] An embodiment of the present invention will be described below with reference to FIGS. 1 and 2. Reference numeral 1 is a side wall of a road tunnel, and 2 is a radiation type fire detector equipped with a solar cell, etc., and a light receiving window 21 serving as a light receiving portion thereof is provided so as to protrude from the side wall 1. 2
Reference numeral 2 denotes a V-shaped change plate, which is provided on the upstream side of the light receiving window 21 with respect to the flow of the airflow 3 so as to generate an upward airflow that prevents the airflow from directly colliding with the light receiving window 21. Airflow 3 above
is a ventilation flow flowing in a fixed direction inside the tunnel at a wind speed of 2 to 8 m/s.

Next, the operation of the change plate 22 will be explained. Tunnel side wall 1
The ventilation flow 3 flowing from a certain direction along the fire detector 2
At the changing plate 22 provided on the wall, the airflow is divided into airflow flowing inside and outside the plate wall. When the main air flow containing floating dust flowing inside the change plate 22 passes over the change plate 22, negative pressure is generated on the secondary side, resulting in a flow as shown by the arrow 31. The flowing air current increases its speed and flows into the negative pressure area from the left and right as shown by the arrow 33 and collides and rises, so the main air current shown by the above arrow 31 is lifted and an upward air current shown by the arrow 32 is generated. In this case, the height is raised to approximately twice the height of the change plate 22.

FIG. 3 shows an example in which the changing plate 22 is formed in an H-shape, and an air current 31 flowing inside the changing plate 22 is lifted by an air current 33 flowing outside, generating an upward air current as shown by an arrow 32. This is shown in Figure 1.

This is similar to the embodiment shown in FIG. Also, this kind of effect is
A similar problem occurs when the change plate 22 is formed into a U-shape.

Furthermore, in the above embodiment, a case was described in which the radiation type fire detector is installed in a road tunnel, but other fire alarms equipped with a similar light-receiving part or light-emitting part such as a light-receiving window or a reflector can also be used. or detectors in anti-theft devices, i.e.
It can be implemented in an alarm device equipped with a light receiving section.

〔effect〕

The alarm of this invention is configured and operates as described above, so that when the airflow flowing on the inner four sides of the change plate passes over the plate at its tip, it generates negative pressure and tries to descend, but the airflow flows on the outside of the plate. Since the air current wraps around and lifts up to generate an upward air current, it is possible to obtain an alarm device that protects the projecting/receiving section up to approximately twice the height of the change plate and is provided with anti-fouling means in the projecting/receiving section.

[Brief explanation of the drawing]

Fig. 1 is a sectional view of the alarm device of the present invention installed on the side wall of a road tunnel, Fig. 2 is a perspective view of the alarm device of Fig. 1, Fig. 3 is a perspective view of another embodiment, and Fig. 4 is a perspective view of the alarm device of the present invention. The figure is a perspective view of a conventional alarm. ■...Tunnel side wall, 2...Fire detector, 21...
・Light receiving window, 22... change plate, 3 river airflow. t7/Kiganjinno], Disaster Prevention Industry Co., Ltd. Figure 1 Figure 2 Figure 3 Figure 4

Claims (1)

[Scope of Claims] 1. Radiation or anti-theft device for fire or burglary where a projecting/receiving part such as a projecting/receiving window or a reflecting mirror is installed on the ceiling or wall of a building where airflow flows from a certain direction. The optical alarm device is characterized in that a change plate is provided on the upstream side of the air flow of the light emitting/receiving part to generate an upward air current so that the airflow does not directly collide with the emitting/receiving part. An alarm equipped with means to prevent contamination of the emitter and receiver. 2. An alarm device equipped with means for preventing staining of the light emitting/receiving section as set forth in claim 1, wherein the change plate is formed in a V-shape. 3. An alarm device equipped with means for preventing staining of the light emitting/receiving section as set forth in claim 1, wherein the change plate is formed in an H-shape. 4. An alarm device equipped with means for preventing staining of the light emitting/receiving section as set forth in claim 1, wherein the change plate is formed in a U-shape.